21001012009 has 8 divisors (see below), whose sum is σ = 21197092032. Its totient is φ = 20805790800.

The previous prime is 21001012007. The next prime is 21001012049. The reversal of 21001012009 is 90021010012.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21001012009 - 2¹ = 21001012007 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21001011983 and 21001012001.

It is not an unprimeable number, because it can be changed into a prime (21001012007) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 165517 + ... + 263434.

It is an arithmetic number, because the mean of its divisors is an integer number (2649636504).

Almost surely, 2^21001012009 is an apocalyptic number.

It is an amenable number.

21001012009 is a deficient number, since it is larger than the sum of its proper divisors (196080023).

21001012009 is a wasteful number, since it uses less digits than its factorization.

21001012009 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 429407.

The product of its (nonzero) digits is 36, while the sum is 16.

The spelling of 21001012009 in words is "twenty-one billion, one million, twelve thousand, nine".